MICROSOFT is working on technology that will give companies more control over whether to prohibit devices that can easily be used to transfer data to and from personal computers.

The technology is due to appear in next version of Windows, dubbed Longhorn, due out in 2006. As devices including Apple's popular iPods become capable of holding more data, some worry that people could use them to steal data or unleash virus attacks on business networks.

Microsoft's goal is to have a system where people can use devices that help them in their work - such as a smart phone full of professional contacts - but not storage devices that could be used to quickly steal data, said Greg Sullivan, a lead product manager.

Mr Sullivan said the company introduced an early version of this technology with Service Pack 2, the security upgrade for the Windows XP operating system completed in early August. But that system works more by "brute force," Mr Sullivan said, and the eventual goal is to make it easier and more refined.

He said the technology was in the planning stages and offered few details.

The technology is part of Microsoft's broader efforts to improve security. The company has tried hard over the last several years to make devices interact easily with Windows, Mr Sullivan said, "and now it's incumbent on us also to make sure we're responding to user needs with regard to security."